Positive type radiosensitive composition and method for forming pattern

ABSTRACT

A positive-tone radiation-sensitive composition including: (A) at least one compound selected from the group consisting of a hydrolyzable silane compound represented by general formula (R 1 ) p Si(X) 4-p  (wherein R 1  is a non-hydrolyzable organic group having 1 to 12 carbon atoms, X is a hydrolyzable group, and p is an integer from 0 to 3), hydrolyzates thereof and condensates thereof; (B) a photoacid generator; and (C) a basic compound. A cured product that is excellent in terms of pattern precision and so on can be obtained by using the composition. The composition can be used as a material for forming optical waveguides.

TECHNICAL FIELD

[0001] The present invention relates to a positive-toneradiation-sensitive composition and a pattern formation method using thecomposition. More specifically, the present invention relates to apositive-tone radiation-sensitive composition from which can be obtaineda cured product that is excellent in terms of pattern precision and soon, a pattern formation method, and an optical waveguide formationmethod using the composition.

BACKGROUND ART

[0002] As conventional positive-tone photoresist materials that usesol-gel materials, for example in Japanese Patent Application Laid-openNo. 10-310642, there are disclosed macromolecular silicone compoundshaving phenolic hydroxyl groups, and macromolecular silicone compoundsin which the hydrogen atoms of the phenolic hydroxyl groups are replacedby specified atoms. Moreover, in Japanese Patent Application Laid-openNo. 11-302382 there is disclosed art in which the hydrogen atoms of thecarboxyl groups or the hydrogen atoms of the carboxyl groups and thehydroxyl groups of a macromolecular silicone compound are replaced witha group unstable to acids. However, with the art disclosed in the abovepatent documents, there have been limitations on the type of monomer orpolymer that can be used.

[0003] Moreover, sol-gel materials are also useful as materials forforming optical waveguides. In this case, because many device materialsare of positive-tone, a positive-tone sol-gel material for formingoptical waveguides has been desirable.

DISCLOSURE OF THE INVENTION

[0004] The present invention was accomplished in view of the above stateof affairs. It is an object of the present invention to provide apositive-tone radiation-sensitive composition containing a polysiloxanetype compound from which can be obtained a cured product havingexcellent pattern precision, regardless of the substituents on thesilicon atoms.

[0005] The above object can be attained by providing a positive-toneradiation-sensitive composition of the present invention that ischaracterized by containing undermentioned components (A) to (C):

[0006] (A) at least one compound selected from the group consisting ofhydrolyzable silane compounds represented by undermentioned generalformula (1), hydrolyzates thereof and condensates thereof

(R¹)_(p)Si(X)_(4-p)   (1)

[0007] (wherein R¹ is a non-hydrolyzable organic group having 1 to 12carbon atoms, X is a hydrolyzable group, and p is an integer from 0 to3);

[0008] (B) a photoacid generator; and

[0009] (C) a basic compound.

[0010] According to the positive-tone radiation-sensitive composition ofthe present invention, a positive-tone radiation-sensitive cured filmcan be formed using general-purpose hydrolyzable silane compounds,without using special hydrolyzable silane compound monomers. Moreover,according to the positive-tone radiation-sensitive composition of thepresent invention, a pattern with excellent resolution can be obtainedthrough patterned exposure.

[0011] Moreover, the positive-tone radiation-sensitive composition ofthe present invention is suitable for forming optical waveguides, and itis possible to reduce waveguide loss in the optical waveguides.

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] A positive-tone radiation-sensitive composition of the presentinvention contains undermentioned components (A) to (C):

[0013] (A) at least one compound selected from the group consisting ofhydrolyzable silane compounds represented by undermentioned generalformula (1), hydrolyzates thereof and condensates thereof

(R¹)_(p)Si(X)_(4-p)   (1)

[0014] (wherein R¹ is a non-hydrolyzable organic group having 1 to 12carbon atoms, X is a hydrolyzable group, and p is an integer from 0 to3);

[0015] (B) a photoacid generator; and

[0016] (C) a basic compound.

[0017] Following is a description of the components (A) to (C) and otheroptional components.

[0018] [Component (A)]

[0019] Out of the constituent components of the positive-toneradiation-sensitive composition, component (A) is a thermosettingcomponent, and comprises at least one compound selected from the groupconsisting of hydrolyzable silane compounds represented by generalformula (1), hydrolyzates thereof and condensates thereof.

[0020] (1) Structure

[0021] In general formula (1) which represents the component (A)structure, a hydrolyzable group represented by X generally indicates agroup that is hydrolyzed to produce a silanol group, or a group thatforms a siloxane condensate, upon heating at a temperature in the rangeof room temperature (25° C.) to 100° C. in the presence of excess waterwithout a catalyst.

[0022] Moreover, p in general formula (1) is an integer from 0 to 3, butis more preferably an integer from 0 to 2, particularly preferably 1.

[0023] Note, however, that in component (A) represented by generalformula (1), some of the hydrolyzable groups represented by X may behydrolyzed, and in this case component (A) becomes a mixture ofhydrolyzable silane compounds and hydrolyzates.

[0024] Moreover, a hydrolyzate of a hydrolyzable silane compoundincludes not only a compound in which alkoxy groups have been convertedinto silanol groups through a hydrolysis reaction, but also a partialcondensate in which some of the silanol groups have condensed with oneanother, and the other silanol groups have not condensed.

[0025] (2) Organic Group R¹

[0026] ‘Non-hydrolyzable’ for the organic group R¹ means a property ofremaining stably under the condition that the hydrolyzable group X ishydrolyzed.

[0027] Here, examples of the organic group R¹ include alkyl groups suchas a methyl group, an ethyl group, a propyl group, a butyl group and ahexyl group; aryl groups such as a phenyl group, a xylyl group and atolyl group, and aralkyl groups such as a benzyl group. The organicgroup R¹ may be straight chain, branched, cyclic, or a combinationthereof.

[0028] (3) Hydrolyzable Group X

[0029] Examples of the hydrolyzable group X in general formula (1)include a hydrogen atom; alkoxy groups having 1 to 12 carbon atoms suchas a methoxy group, an ethoxy group, a propoxy group and a butoxy group;halogen atoms such as a chlorine atom, an iodine atom or a fluorineatom; an amino group, and acyloxy groups.

[0030] (4) Examples of Hydrolyzable Silane Compounds

[0031] Examples of hydrolyzable silane compounds represented by generalformula (1) (sometimes referred to merely as ‘silane compounds’) includesilane compounds substituted with four hydrolyzable groups such astetrachlorosilane, tetraaminosilane, tetraacetoxysilane,tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane,tetraphenoxysilane, tetrabenzyloxysilane, trimethoxysilane andtriethoxysilane; silane compounds substituted with three hydrolyzablegroups such as methyltrichlorosilane, methyltrimethoxysilane,methyltriethoxysilane, methyltributoxysilane, ethyltrimethoxysilane,ethyltriisopropoxysilane, ethyltributoxysilane, butyltrimethoxysilane,pentafluorophenyltrimethoxysilane, phenyltrimethoxysilane,d3-methyltrimethoxysilane, nonafluorobutylethyltrimethoxysilane andtrifluoromethyltrimethoxysilane; silane compounds substituted with twohydrolyzable groups such as dimethyldichlorosilane,dimethyldiaminosilane, dimethyldiacetoxysilane, dimethyldimethoxysilane,diphenyldimethoxysilane and dibutyldimethoxysilane; and silane compoundssubstituted with one hydrolyzable group such as trimethylchlorosilane,hexamethyldisilazane, trimethylsilane, tributylsilane,trimethylmethoxysilane and tributylethoxysilane.

[0032] Moreover, there are no particular limitations on the conditionsunder which the above silane compound is hydrolyzed or condensed, but asone example, it is preferable to carry out the hydrolysis orcondensation through the following three steps 1) to 3).

[0033] 1) The hydrolyzable silane compound represented by generalformula (1) and a prescribed amount of water are put into a vesselequipped with a stirrer.

[0034] 2) Next, an organic solvent is put into the vessel whileadjusting the viscosity of the solution, thus producing a mixedsolution.

[0035] 3) The mixed solution obtained is heated and stirred for 1 to 24hours in an air atmosphere at a temperature between 0° C. and theboiling point of the organic solvent or the hydrolyzable silanecompound. Note that during the heating and stirring, it is preferable toconcentrate the mixed solution through distillation or replace thesolvent as required.

[0036] Moreover, it is preferable to use a catalyst when hydrolyzing orcondensing the silane compound. Examples of the type of this catalystinclude metal chelate compounds, organic acids, inorganic acids, organicbases, and inorganic bases.

[0037] Out of these catalysts, metal chelate compounds, organic acidsand inorganic acids are preferable. Titanium chelate compounds, aluminumchelate compounds and organic acids are particularly preferable. Onecatalyst may be used, or two or more may be used together.

[0038] Moreover, the amount used of the catalyst is generally in therange of 0.001 to 10 parts by weight, preferably 0.005 to 10 parts byweight, per 100 parts by weight (in terms of completely hydrolyzed andcondensed content) of the silane compound constituting component (A).

[0039] Note that in the present invention, ‘completely hydrolyzed andcondensed content’ means that 100% of the hydrolyzable groups in thesilane compound represented by general formula (1) have been hydrolyzedinto SiOH groups, and have been condensed completely into a siloxanestructure.

[0040] (5) Weight Average Molecular Weight of Hydrolyzate

[0041] It is preferable for the hydrolyzable silane compoundconstituting component (A) to be in the form of a hydrolyzate in whichsome or all of the hydrolyzable groups have been hydrolyzed, and in thiscase, the weight average molecular weight of the hydrolyzate ispreferably in the range of 500 to 30,000.

[0042] The reasons for this are that if the weight average molecularweight of the hydrolyzate is less than 500, then the film formingability of the coating film may drop, whereas if the weight averagemolecular weight of the hydrolyzate exceeds 30,000, then the thermalcuring ability may rise, and hence the solubility to the developingsolution may drop.

[0043] Accordingly, it is more preferable to make the weight averagemolecular weight of the hydrolyzate be in the range of 800 to 15,000.

[0044] Note that the weight average molecular weight of the hydrolyzatecan be measured by gel permeation chromatography (hereinafterabbreviated to ‘GPC’), and can be calculated in terms of polystyrene asa standard material.

[0045] [Component (B)]

[0046] Component (B) is a photoacid generator, and is defined as acompound that is able to neutralize the basic compound that constitutescomponent (C) described later, upon being irradiated with radiation suchas ultraviolet radiation.

[0047] (1) Type

[0048] Examples of the type of the photoacid generator are onium saltshaving a structure represented by general formula (2) (first groupcompounds), and sulfonic acid derivatives having a structure representedby general formula (3) (second group compounds).

[R² _(a)R³ _(b)R⁴ _(c)R⁵ _(d)W]^(+m)[MZ_(m+n)]^(−m)   (2)

[0049] (In general formula (2), the cation is an onium ion. W is S, Se,Te, P, As, Sb, Bi, O, I, Br, Cl or —N≡N. R², R³, R⁴ and R⁵ are the sameorganic group or different organic groups. Each of a, b, c and d is aninteger from 0 to 3. The sum of a+b+c+d is equal to the valency of W. Mis a metal or metalloid constituting the central atom in the halidecomplex [MZ_(m+n)], for example B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In,Ti, Zn, Sc, V, Cr, Mn or Co. Z is a halogen atom such as F, Cl or Br, oran aryl group. m is the net charge on the halide complex ion. n is thevalency of M.)

Q_(s)-[S(═O)₂-R⁶]_(t)   (3)

[0050] (In general formula (3), Q is a monovalent or bivalent organicgroup, R⁶ is a monovalent organic group having 1 to 12 carbon atoms, sis 0 or 1, and t is 1 or 2.)

[0051] First, the onium salts that are the first group compounds arecompounds that are able to discharge an acidic active substance uponreceiving light.

[0052] Here, specific examples of the anion [MZ_(m+n)] in generalformula (2) include tetrafluoroborate(BF₄ ⁻), hexafluorophosphate(PF₆⁻), hexafluoroantimonate(SbF₆ ⁻), hexafluoroarsenate(AsF₆ ⁻),hexachloroantimonate(SbCl₆ ⁻), tetraphenylborate,tetrakis(trifluoromethylphenyl)borate, andtetrakis(pentafluoromethylphenyl)borate.

[0053] Moreover, it is also favorable to use an anion represented by thegeneral formula [MZ_(n)OH⁻] instead of the anion [MZ_(m+n)] in generalformula (2). Furthermore, an onium salt having another anion such as aperchlorate ion (ClO₄ ⁻), a trifluoromethanesulfonate ion (CF₃SO₃ ⁻), afluorosulfonate ion (FSO₃ ⁻), a toluenesulfonate ion, atrinitrobenzenesulfonate anion, or a trinitrotoluenesulfonate anion canbe used.

[0054] Moreover, examples of commercially sold ones of the first groupcompounds include Sun-aid SI-60, SI-80, SI-100, SI-60L, SI-80L, SI-100L,SI-L145, SI-L150, SI-L160, SI-L110 and SI-L147 (all made by SanshinChemical Industry Co., Ltd.), UVI-6950, UVI-6970, UVI-6974 and UVI-6990(all made by Union Carbide Corporation), Adeka Optomer SP-150, SP-151,SP-170 and SP-171 (all made by Asahi Denka Co., Ltd.), Irgacure 261(made by Ciba Specialty Chemicals), CI-2481, CI-2624, CI-2639 andCI-2064 (all made by Nippon Soda Co., Ltd.), CD-1010, CD-1011 andCD-1012 (all made by Sartomer Company, Inc.), DS-100, DS-101, DAM-101,DAM-102, DAM-105, DAM-201, DSM-301, NAI-100, NAI-101, NAI-105, NAI-106,SI-100, SI-101, SI-105,.SI-106, PI-105, NDI-105, BENZOIN TOSYLATE,MBZ-101, MBZ-301, PYR-100, PYR-200, DNB-101, NB-101, NB-201, BBI-101,BBI-102, BBI-103 and BBI-109 (all made by Midori Kagaku K.K.), P,I-061T,P,I-062T, P,I-020T and P,I-022T (all made by Nippon Kayaku Co., Ltd.),and IBPF and IB,F (made by Sanwa Chemical Co., Ltd.).

[0055] Moreover, out of the first group compounds described above,particularly effective onium salts are aromatic onium salts. Diaryliodonium salts represented by undermentioned general formula (4) areparticularly preferable.

[R⁷—Ar¹—I⁺—Ar²—R⁸][Y⁻]  General formula (4)

[0056] (In the formula, each of R⁷ and R⁸ is a monovalent organic group,and may be the same or different. At least one of R⁷ and R⁸ have analkyl group having four or more carbon atoms. Each of Ar¹ and Ar² is anaromatic group, and may be the same or different. Y⁻ is a monovalentanion, and is an anion selected from group III and group V fluorideanions, ClO₄ ⁻, and CF₃—SO₃ ⁻).

[0057] Examples of such diaryl iodonium salts include

[0058] (4-n-decyloxyphenyl)phenyliodonium hexafluoroantimonate,

[0059] [4-(2-hydroxy-n-tetradecyloxy)phenyl]phenyliodoniumhexafluoroantimonate,

[0060] [4-(2-hydroxy-n-tetradecyloxy)phenyl]phenyliodoniumtrifluorosulfonate,

[0061] [4-(2-hydroxy-n-tetradecyloxy)phenyl]phenyliodoniumhexafluorophosphate,

[0062] [4-(2-hydroxy-n-tetradecyloxy)phenyl]phenyliodoniumtetrakis(pentafluorophenyl)borate,

[0063] bis(4-t-butylphenyl)iodonium hexafluoroantimonate,

[0064] bis(4-t-butylphenyl)iodonium hexafluorophosphate,

[0065] bis(4-t-butylphenyl)iodonium trifluorosulfonate,

[0066] bis(4-t-butylphenyl)iodonium tetrafluoroborate,

[0067] bis(dodecylphenyl)iodonium hexafluoroantimonate,

[0068] bis(dodecylphenyl)iodonium tetrafluoroborate,

[0069] bis(dodecylphenyl)iodonium hexafluorophosphate, andbis(dodecylphenyl)iodonium trifluoromethylsulfonate. It is possible touse one diaryl iodonium salt or a combination of two or more.

[0070] Moreover, examples of commercially sold diaryl iodonium saltsinclude, for example, D1012 made by Sartomer Company, Inc., IBPF andIBCF made by Sanwa Chemical Co., Ltd., and BBI-101, BBI-102, BBI-103 andBBI-109 made by Midori Kagaku K.K.

[0071] Next, a description will be given of the second group compounds.Examples of the sulfonic acid derivatives represented by general formula(3) include disulfones, disulfonyl diazomethane derivatives, disulfonylmethane derivatives, sulfonyl benzoyl methane derivatives,imidosulfonates, benzoin sulfonates, 1-oxy-2-hydroxy-3-propyl alcoholsulfonates, pyrogallol trisulfonates, and benzyl sulfonates.

[0072] Moreover, out of the sulfonic acid derivatives represented bygeneral formula (3), imidosulfonates are particularly preferable. Out ofimidosulfonates, trifluoromethylsulfonate derivatives are yet morepreferable.

[0073] (2) Amount Added

[0074] In the present invention, the proportion of the photoacidgenerator in the positive-tone radiation-sensitive composition isgenerally 0.01 to 15 parts by weight, preferably 0.05 to 10 parts byweight, per 100 parts by weight (in terms of completely hydrolyzed andcondensed content) of component (A).

[0075] If the proportion of the photoacid generator is less than 0.01parts by weight, then the ability to neutralize the basic compound willdrop, and hence the rate of thermal curing by component (C) may bedominant. If the proportion of the photoacid generator exceeds 15 partsby weight, then photo-curing of component (A) by the generated acid maytend to become dominant.

[0076] Moreover, in the present invention, it is also preferable to usea photosensitizer together with the photoacid generator, since energyrays such as light can be absorbed more effectively, and hence thesensitivity of the photoacid generator can be increased.

[0077] Examples of such photosensitizers include thioxanthone,diethylthioxanthone, and thioxanthone derivatives; anthraquinone,bromoanthraquinone, and anthraquinone derivatives; anthracene,bromoanthracene, and anthracene derivatives; perylene and perylenederivatives; xanthone, thioxanthone, and thioxanthone derivatives; andcoumarin and ketocoumarin.

[0078] Moreover, out of these photosensitizers, particularly preferablecompounds are diethylthioxanthone and bromoanthracene.

[0079] In the case of using such a photosensitizer, the photosensitizeris preferably used in a proportion of 0.1 to 1 wt % relative to thephotoacid generator.

[0080] [Component (C)]

[0081] Component (C), which is a basic compound, is defined as acompound that promotes the curing of component (A) through heat, and isneutralized by the acid generated from component (B).

[0082] (1) Type

[0083] As the basic compound used as component (C), anitrogen-containing organic compound for which the basicity does notchange upon exposure with radiation during the pattern formation processis preferable.

[0084] Examples of such nitrogen-containing organic compounds arecompounds represented by undermentioned general formulae (5) and (6)(hereinafter referred to as ‘nitrogen-containing compounds (I)’).

[0085] (R⁹, R¹⁰ and R¹¹ in general formula (5) and R¹², R¹³ ₁ R¹⁴ andR¹⁵ in general formula (6) are independent each other, and each of theserepresents a hydrogen atom, an optionally substituted alkyl group having1 to 15 carbon atoms, or an optionally substituted aryl group. Moreover,Y in general formula (6) represents a quaternary ammonium salt counteranion.) Moreover, examples of other nitrogen-containing organiccompounds include diamino compounds having two nitrogen atoms in onemolecule (hereinafter referred to as ‘nitrogen-containing compounds(II)’), diamino polymers having three or more nitrogen atoms in onemolecule (hereinafter referred to as ‘nitrogen-containing compounds(III)’), amide group-containing compounds, urea compounds, andnitrogen-containing heterocyclic compounds.

[0086] Here, examples of the nitrogen-containing compounds (I) includemonoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonylamine, and n-decylamine; dialkylamines such as di-n-butylamine,di-n-pentylamine, di-n-hexylamine, di-n-heptylamine, di-n-octylamine,di-n-nonylamine, and di-n-decylamine; trialkylamines such astriethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine,tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine,and tri-n-decylamine; tetraalkylamine salts such as tetramethylammoniumhydroxide, tetraethylammonium hydroxide, and tetrapropylammoniumhydroxide; aromatic amines such as aniline, N-methylaniline,N,N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline,4-nitroaniline, diphenylamine, triphenylamine, and 1-naphthylamine; andalkanolamines such as ethanolamine, diethanolamine, and triethanolamine.

[0087] Moreover, examples of the nitrogen-containing compounds (II)include ethylenediamine, N,N,N′,N′-tetramethylethylenediamine,tetramethylenediamine, hexaamethylenediamine,N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine,N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine,4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylether,4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2′-bis(4-aminophenyl) propane, 2-(3-aminophenyl)-2-(4-aminophenyl)propane,2-(4-aminophenyl)-2-(3-hydroxyphenyl)propane,2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane,1,4-bis[1-(4-aminophenyl)-1-methylethyl]benzene, and1,3-bis[1-(4-aminophenyl)-1-methylethyl]benzene.

[0088] Moreover, examples of the nitrogen-containing compounds (III)include polyethyleneimine, polyallylamine, and a polymer ofdimethylaminoethylacrylamide.

[0089] Moreover, examples of amide group-containing compounds includeformamide, N-methylformamide, N,N-dimethylformamide, acetoamide,N-methylacetoamide, N,N-dimethylacetoamide, propionamide, benzamide,pyrrolidone, and N-methylpyrrolidone.

[0090] Moreover, examples of urea compounds include urea, methylurea,1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea,1,3-diphenylurea, and tributylthiourea.

[0091] Moreover, examples of nitrogen-containing heterocyclic compoundsinclude imidazoles such as imidazole, benzimidazole, 2-methylimidazole,4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, and4-methyl-2-phenylimidazole; pyridines such as pyridine,2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine,2-phenylpyridine, 4-phenylpyridine, N-methyl-4-phenylpyridine, nicotine,nicotinic acid, nicotinic acid amide, quinoline, 8-oxyquinoline, andacridine; and pyrazine, pyrazole, pyridazine, quinozaline, purine,pyrrolidine, piperidine, morpholine, 4-methylmorpholine, piperazine,1,4-dimethylpiperazine, and 1,4-diazabicyclo[2.2.2]octane.

[0092] Out of these nitrogen-containing organic compounds, preferableones include the nitrogen-containing compounds (I) and thenitrogen-containing heterocyclic compounds. Moreover, out of thenitrogen-containing compounds (I), tetraalkylamine salts areparticularly preferable. Out of the nitrogen-containing heterocycliccompounds, pyridines are particularly preferable.

[0093] One such basic compound can be used alone, although it is alsofavorable to use two or more mixed together.

[0094] Moreover, it is also favorable to use such a nitrogen-containingbasic compound together with an acidic compound.

[0095] Examples of the acidic compound used in this case includemonocarboxylic acids such as formic acid, acetic acid and propionicacid; and dicarboxylic acids such as oxalic acid, malonic acid, succinicacid, adipic acid, maleic acid and succinic acid.

[0096] (2) Amount to be Added

[0097] The proportion of the basic compound in the positive-toneradiation-sensitive composition of the present invention is generally0.001 to 15 parts by weight, preferably 0.001 to 10 parts by weight,particularly preferably 0.005 to 5 parts by weight, per 100 parts byweight (in terms of completely hydrolyzed and condensed content) ofcomponent (A).

[0098] If the proportion of the basic compound is less than 0.001 partsby weight, then depending on the processing conditions, condensation ofcomponent (A) may be poor and insufficient for thermal curing. If theproportion of the basic compound exceeds 15 parts by weight, then thethermal curing reaction of component (A) may proceed too much, resultingin the cured product being insoluble in the developing solution.

[0099] [Component (D)]

[0100] The positive-tone radiation-sensitive composition of the presentinvention may contain an acrylic polymer as a component (D) in additionto components (A) to (C).

[0101] Examples of component (D) include a (meth) acrylic copolymercontaining hydrolyzable silyl groups.

[0102] By using component (D), the cracking resistance of thepositive-tone radiation-sensitive composition can be improved, andmoreover the dielectric constant can be made lower than in the case ofcarrying out the processing with only component (A).

[0103] Moreover, when forming the radiation-sensitive composition of thepresent invention, it is particularly preferable to use a co-condensateobtained by reacting component (A) and component (D) together inadvance.

[0104] By reacting component (A) and component (D) together in advancein this way, the tendency for phase separation between component (A) andcomponent (D) can be reduced, and hence the transparency and so on ofthe cured film obtained can be improved.

[0105] Following is a description of hydrolyzable silyl group-containingvinyl polymers used as component (D).

[0106] [1] Type and Manufacturing Method

[0107] A hydrolyzable silyl group-containing vinyl polymer used in afirst embodiment is defined as a polymer of a vinyl monomer having atleast one hydrolyzable silyl group in the molecule thereof, asrepresented by general formula (7). The hydrolyzable silyl group ingeneral formula (7) is the same as the hydrolyzable silyl group ingeneral formula (1).

[0108] (General Formula (7))

[0109] [In general formula (7), each R¹⁶ is independently a hydrogenatom, a halogen atom, or a monovalent organic group having 1 to 12carbon atoms. R¹⁷ is a single bond or a bivalent organic group having 1to 15 carbon atoms. R¹⁸ and X′ represent an alkoxy group, a halogen atomor an acyloxy group. m represents an integer from 0 to 2.]

[0110] Moreover, there are no particular limitations on the method ofintroducing the hydrolyzable silyl groups into the vinyl polymer whenmanufacturing such a hydrolyzable silyl group-containing vinyl polymer,but it is preferable to adopt, for example, the first manufacturingmethod or the second manufacturing method described below.

[0111] (First Manufacturing Method)

[0112] The first manufacturing method is a method in which thehydrolyzable silyl group-containing vinyl polymer is manufactured bypolymerizing polymerizable unsaturated monomers having hydrolyzablesilyl groups, or by copolymerizing polymerizable unsaturated monomershaving hydrolyzable silyl groups and polymerizable unsaturated monomersnot having hydrolyzable silyl groups.

[0113] Examples of polymerizable unsaturated monomers having ahydrolyzable silyl group used in the first manufacturing method include(meth)acryloxysilanes such as (meth)acryloxypropyltrimethoxysilane,acryloxypropyltrimethoxysilane, (meth)acryloxypropyltriethoxysilane,(meth)acryloxypropylmethyldimethoxysilane,(meth)acryloxypropyltrichlorosilane andbis(methacryloxypropyl)dimethoxysilane; and vinylsilanes such asvinyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane,divinyldimethoxysilane and divinyldiethoxysilane. Note that one of theabove polymerizable unsaturated monomers having hydrolyzable silylgroups may be polymerized alone, or two or more maybe polymerized incombination.

[0114] Moreover, polymerizable unsaturated monomers not having ahydrolyzable silyl group are compounds having in the molecule thereof anethylenic unsaturated bond that will undergo radical polymerization, andare selected from monofunctional monomers having one ethylenicunsaturated bond per molecule.

[0115] Examples of such compounds (which is monofunctional monomers) nothaving a hydrolyzable silyl group include (meth) acrylic acid,(meth)acrylates, acrylamides, N-vinyl compounds, styrenes, vinyl ethers,vinyl esters, halogenated olefins, and dienes.

[0116] Examples of preferable (meth)acrylates include alkyl (meth)acrylates, terminal hydroxy group (meth) acrylates, and aminogroup-containing (meth)acrylates. Specific examples of such(meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate,butyl (meth)acrylate, cyclohexyl (meth)acrylate,7-amino-3,7-dimethyloctyl (meth)acrylate, isobornyloxyethyl(meth)acrylate, isobornyl (meth)acrylate, 2-ethylhexyl (meth)acrylate,ethyldiethyleneglycol (meth)acrylate, dimethylaminoethyl (meth)acrylate,diethylaminoethyl (meth)acrylate, lauryl (meth)acrylate, allyl(meth)acrylate, dicyclopentadiene (meth)acrylate,dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate,N,N-dimethyl (meth)acrylamide tetrachlorophenyl (meth)acrylate,2-tetrachlorophenoxyethyl (meth)acrylate, tetrahydrofurfuryl(meth)acrylate, tetrabromophenyl (meth)acrylate,2-tetrabromophenoxyethyl (meth)acrylate, 2-trichlorophenoxyethyl(meth)acrylate, tribromophenyl (meth)acrylate, 2-tribromophenoxyethyl(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydropropyl(meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenoxyethyl(meth)acrylate, butoxyethyl (meth)acrylate, pentachlorophenyl(meth)acrylate, pentabromophenyl (meth)acrylate, polyethylene glycolmono(meth)acrylate, polypropylene glycol mono(meth)acrylate, bornyl(meth) acrylate, methyltriethylenediglycol (meth) acrylate, glycidyl(meth)acrylate, and β-(3,4-epoxycyclohexyl)ethyl (meth)acrylate.

[0117] Moreover, preferable acrylamides include (meth)acryloylmorpholine, isobutoxymethyl (meth)acrylamide, t-octyl (meth)acrylamide,diacetone (meth)acrylamide, and vinyl caprolactam. Examples of N-vinylcompounds include N-vinylpyrrolidone and N-vinylcarbazole.

[0118] Moreover, preferable styrenes include styrene, α-methylstyrene,methylstyrene, methoxystyrene, hydroxystyrene, and chloromethylstyrene.Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether,butyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether,and nonafluorobutylethyl vinyl ether.

[0119] Moreover, preferable vinyl esters include vinyl acetate, vinylpropionate, and vinyl laurate.

[0120] Moreover, preferable halogenated olefins include vinylidenefluoride, tetrafluoroethylene, hexafluoropropene, and vinylidenechloride.

[0121] Moreover, preferable dienes include butadiene and isoprene.

[0122] Note that one of these monofunctional monomers not having ahydrolyzable silyl group may be used alone, or two or more may be usedin combination.

[0123] Moreover, out of the above-mentioned polymerizable unsaturatedmonomers not having a hydrolyzable silyl group, it is particularlypreferable to use an alkyl (meth)acrylate, since there is no reductionof the thermal curing ability due to nonexistence of an amide structureor amine structure, and also light resistance is good due tononexistence of an aromatic ring.

[0124] Examples of such alkyl (meth)acrylates include methyl(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl(meth)acrylate, isobornyl (meth)acrylate, lauryl (meth)acrylate,butoxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate,bornyl (meth)acrylate, methyltriethylenediglycol (meth)acrylate,2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, andβ-(3,4-epoxycyclohexyl)ethyl (meth)acrylate.

[0125] Moreover, commercially sold ones of such monofunctional monomersinclude Aronix M-101, M-102, M-111, M-113, M-117, M-152 and TO-1210 (allmade by Toagosei Co., Ltd.), KAYARADT, -110S, R-564 and R-128H (all madeby Nippon Kayaku Co., Ltd.), and Viscoat 192, Viscoat 220, Viscoat2311HP, Viscoat 2000, Viscoat 2100, Viscoat 2150, Viscoat 8F and Viscoat17F (all made by Osaka Organic Chemical Industry Ltd.).

[0126] A publicly known method can be adopted as the method ofcopolymerizing the vinyl monomers and the polymerizable unsaturatedmonomers having hydrolyzable silyl groups.

[0127] For example, the copolymer may be manufactured by heating andstirring the monomers in an organic solvent or without a solvent, in thepresence of a thermal radical polymerization initiator such as an azocompound, a peroxide, or a redox polymerization initiator comprising acombination of an oxidizing agent and a reducing agent.

[0128] Here, it is possible to use water instead of an organic solvent,and in this case the manufacture is carried out in the presence of apublicly known surfactant added during emulsion polymerization.

[0129] Moreover, there are no particular limitations on the proportionsof the polymerizable unsaturated monomers having hydrolyzable silylgroups and the vinyl monomers in the reaction. For example, taking thedegree of polymerization of the polymerizable unsaturated monomershaving hydrolyzable silyl groups to be t, and taking the degree ofpolymerization of the vinyl monomers to be u, it is preferable to maket/(t+u) have a value in the range of 0.001 to 1.000. If the value oft/(t+u) is outside such a range, then the light resistance and chemicalresistance of the cured product obtained tend to drop. It is morepreferable to make t/(t+u) have a value in the range of 0.01 to 0.500.

[0130] Furthermore, it is also favorable to use a polymerizationinitiator that decomposes and initiates polymerization through lightinstead of a thermal radical polymerization initiator, whereby acopolymer on a par with that obtained using a thermal radicalpolymerization initiator can be manufactured.

[0131] Out of these methods of manufacturing the hydrolyzable silylgroup-containing vinyl polymer, a preferable one is a method in whichthe manufacture is carried out in an organic solvent in the presence ofa thermal radical polymerization initiator.

[0132] In this case, as the organic solvent, it is preferable to use anorganic solvent having a boiling point at one atmosphere in the range of30° C. to 250° C., more preferably 50° C. to 200° C. Examples of suchorganic solvents include ethers such as dibutyl ether, tetrahydrofuran,ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and1,3-dioxane; ketones such as acetone, methyl ethyl ketone, methylisobutyl ketone, and cyclohexanone; esters such as ethyl acetate, butylacetate, amyl acetate, and γ-butyrolactone; alcohols such as methanol,ethanol, isopropanol, butanol, and carbitol; aromatic hydrocarbons suchas benzene, toluene, and xylene; hydrocarbons such as cyclohexane,n-hexane, and ligroin; amides such as dimethylformamide,dimethylacetamide, and N-methylpyrrolidone; and halogenated hydrocarbonssuch as carbon tetrachloride and methylene chloride. Out of these,alcohols and ketones are particularly preferable organic solvents.

[0133] Moreover, it is preferable for the organic solvent to have a lowmoisture content to secure stability of the hydrolyzable silyl groups.This moisture content is, for example, preferably not more than 1 wt %,more preferably not more than 0.1 wt %.

[0134] Moreover, there are no particular limitations on the polymersolid concentration in the solution so long as the reaction proceedsuniformly and smoothly, but this solid concentration is generally in therange of 10 to 80 wt %, preferably in the range of 20 to 60 wt %.

[0135] (Second Manufacturing Method)

[0136] The second manufacturing method is a method in which thehydrolyzable silyl group-containing vinyl polymer is manufactured bychemically reacting a vinyl polymer having reactive organic groups witha compound having hydrolyzable silyl groups. In this case, as thecompound having hydrolyzable silyl groups, one that has been hydrolyzedin advance, or one that has been hydrolyzed and condensed in advance,can be used.

[0137] A publicly known method can be used when introducing thehydrolyzable silyl groups through a chemical reaction, for example:

[0138] 1) a hydrosilylation reaction in which a trialkoxysilane is addedto a polymer having unsaturated double bonds in the presence of atransition metal catalyst;

[0139] 2) a method in which an alkoxysilane having a mercapto group oran amino group is added to a polymer having epoxy groups;

[0140] 3) a method in which silylation is carried out through urethanelinkages by reacting a polymer having hydroxy groups with analkoxysilane having an isocyanate group; etc.

[0141] As the method of adding the hydrolyzable silyl group-containingvinyl polymer manufactured using the first or second manufacturingmethod described above, in general the hydrolyzable silylgroup-containing vinyl polymer is mixed directly into the hydrolyzablesilane compound used as component (A).

[0142] Note, however, that it is also favorable to mix component (A)with the hydrolyzable silyl group-containing vinyl polymer in a vessel,and then carry out the hydrolyzable silane hydrolysis and condensationin the same vessel. In the case of carrying out the preparation in thisway, a polymer is formed in which component (A) and component (D) arecondensed together through siloxane linkages, and hence phase separationdoes not occur. Manufacture of the positive-tone radiation-sensitivecomposition thus becomes easier, and the transparency of the cured filmobtained is improved.

[0143] [2] Amount of Vinyl Polymer to be Added

[0144] Next, a description will be given of the amount (i.e. proportion)of the vinyl polymer to be added used in the first embodiment. There areno particular limitations on the amount added of the vinyl polymer, butit is preferable for this amount to be in the range of 1 to 80 parts byweight per 100 parts by weight of component (A). If the amount of thevinyl polymer to be added is less than 1 part by weight, then there willbe little change in cracking resistance compared with the case thatcomponent (A) is used alone. On the other hand, if the amount of thevinyl polymer to be added exceeds 80 parts by weight, then the thermalresistance of the cured product obtained from the positive-toneradiation-sensitive composition will tend to drop.

[0145] From the viewpoint of making the balance between the crackingresistance and the thermal resistance yet better, it is more preferablefor the amount of the vinyl polymer to be added to be in the range of 5to 60 parts by weight, yet more preferably 10 to 40 parts by weight, per100 parts by weight of component (A)

[0146] [3] Weight Average Molecular Weight

[0147] There are no particular limitations on the weight averagemolecular weight of the vinyl polymer, but it is preferable, forexample, for this weight average molecular weight to be in the range of1,000 to 100,000. If the weight average molecular weight of the vinylpolymer is less than 1,000, then the flexibility will tend to drop,whereas if the weight average molecular weight exceeds 1,000,000, thenthe transparency of the cured film will tend to become poor, and thesolubility to the developing solution will tend to drop.

[0148] From the viewpoint of making the balance between the flexibilityand the transparency yet better, it is more preferable to make theweight average molecular weight of the vinyl polymer be in the range of3,000 to 50,000, yet more preferably 5,000 to 30,000.

[0149] [Organic Solvent]

[0150] In the present invention, it is generally preferable to use thecomponents (A) to (C), along with component (D) as required, dissolvedin an organic solvent. By using an organic solvent, the storagestability of the positive-tone radiation-sensitive composition can beimproved, and a suitable viscosity can be obtained. Accordingly, acoating film having an uniform thickness can be formed.

[0151] (1) Type of Organic Solvent

[0152] Any type of the organic solvent can be selected, provided theobjects and effects of the present invention are not impaired. It isgenerally preferable to use an organic solvent that has a boiling pointat atmospheric pressure in the range of 50 to 200° C., and in which eachof the constituent components dissolves uniformly.

[0153] Examples of such organic solvents include at least one compoundselected from the group consisting of ether type organic solvents, estertype organic solvents, ketone type organic solvents, aromatichydrocarbon type organic solvents, and alcohol type organic solvents.Out of these, alcohols and ketones are particularly preferable.

[0154] The reason for this is that by using such an organic solvent, thestorage stability of the positive-tone radiation-sensitive compositioncan be further improved.

[0155] Moreover, examples of a yet particularly preferable organicsolvent include at least one compound selected from the group consistingof propylene glycol monomethyl ether, ethyl lactate, methyl isobutylketone, methyl amyl ketone, toluene, xylene, and methanol.

[0156] (2) Amount of Organic Solvent to be Added

[0157] The amount of the organic solvent to be added is preferably inthe range of 10 to 99 wt %, where the total amount of the positive-toneradiation-sensitive composition is taken as 100 wt %.

[0158] If the amount of the organic solvent to be added is less than 10wt %, it may be difficult to regulate the viscosity of the positive-toneradiation-sensitive composition. If the amount of the organic solvent tobe added exceeds 99 wt %, it may be difficult to form a curedcomposition having a sufficient thickness.

[0159] [Reactive Diluent]

[0160] The positive-tone radiation-sensitive composition of the presentinvention may contain a reactive diluent as required. By including areactive diluent, cure shrinkage of the coating film can be reduced, andthe mechanical strength can be controlled.

[0161] Moreover, in the case of using a radical-polymerizable reactivediluent, by further adding a radical generator, the photoreactivity canbe regulated, and in the case of using a cationic-polymerizable reactivediluent, the photoreactivity and the mechanical properties can beregulated.

[0162] (1) Type of Reactive Diluent

[0163] Regarding the type of the reactive diluent, it is preferable toblend in a cationic-polymerizable monomer and an ethylenic unsaturatedmonomer, or one of these monomers.

[0164] Here, a cationic-polymerizable monomer, which is a reactivediluent, is defined as an organic compound that undergoes apolymerization reaction or a crosslinking reaction upon irradiation withlight in the presence of a photoacid generator. Examples of thecationic-polymerizable monomer include epoxy compounds, oxetanecompounds, oxolane compounds, cyclic acetal compounds, cyclic lactonecompounds, thiirane compounds, thietane compounds, vinyl ethercompounds, spiroorthoester compounds which are reaction products betweenan epoxy compound and a lactone, ethylenic unsaturated compounds, cyclicether compounds, cyclic thioether compounds, and vinyl compounds. One ofthese cationic-polymerizable monomers may be used alone, or two or moremay be used in combination.

[0165] There are no particular limitations on ethylenic unsaturatedmonomers, so long as they are compounds having an ethylenic unsaturatedbonds in the molecule thereof. For example, monofunctional monomershaving one ethylenic unsaturated bond per molecule, and polyfunctionalmonomers having two or more ethylenic unsaturated bonds per molecule arefavorable.

[0166] (2) Amount of Reactive Diluent to be Added

[0167] There are no particular limitations on the amount of the reactivediluent, but this amount is generally in the range of 0.1 to 100 partsby weight, preferably 0.5 to 80 parts by weight, more preferably 1 to 50parts by weight, per 100 parts by weight (in terms of completelyhydrolyzed and condensed content) of component (A).

[0168] [Inorganic Particles]

[0169] The positive-tone radiation-sensitive composition of the presentinvention may contain inorganic particles as required, whereby the cureshrinkage of the coating film can be reduced, and the mechanicalproperties and thermal resistance of the cured composition formed can beimproved.

[0170] (1) Type etc. of Inorganic Particles

[0171] Examples of inorganic particles that can be used in the presentinvention are silica, alkali metal oxides, alkaline earth oxides, andoxides of Ti, Zr, Al, B, Sn, P and so on.

[0172] The average particle size of the inorganic particles ispreferably in the range of 0.001 to 20 μm, and in particular, from thestandpoint of a transparent cured film formed, is more preferably in therange of 0.001 to 0.2 μm, and yet more preferably in the range of 0.001to 0.01 μm.

[0173] Moreover, it is preferable to select the inorganic particles suchthat the difference between the refractive index of the inorganicparticles (temperature 25° C., Na-D line; likewise hereinafter) and therefractive index of the positive-tone radiation-sensitive composition isnot more than 0.02 (−). By making the refractive index difference besuch a value, the transparency of the cured film can be furtherimproved.

[0174] Moreover, the specific surface area of the inorganic particles ispreferably in the range of 0.1 to 3,000 m²/g, more preferably 10 to1,500 m²/g.

[0175] Furthermore, there are no particular limitations on the form ofthe inorganic particles, but this form is preferably at least one formselected from the group consisting of a spherical form, a hollow form, aporous form, a rod-like form, a plate-like form, a fiber-like form, andan irregular form. Note, however, that from the viewpoint of improveddispersibility, it is particularly preferable to use spherical silicaparticles.

[0176] Moreover, it is also favorable to use a dispersion of silicaparticles as the inorganic particles. Furthermore, it is preferable touse colloidal silica, since then a particularly high transparency can beobtained.

[0177] (2) Amount of Inorganic Particles to be Added

[0178] There are no particular limitations on the amount of theinorganic particles, but this amount is generally 10 to 250 parts byweight, preferably 20 to 200 parts by weight, particularly preferably 30to 150 parts by weight, per 100 parts by weight (in terms of completelyhydrolyzed and condensed content) of component (A).

[0179] As additives other than the constituent components describedabove, it is favorable to add macromolecular resins other than component(D), for example an epoxy resin, an acrylic resin, a polyamide resin, apolyamide-imide resin, a polyurethane resin, a polybutadiene resin, apolychloroprene resin, a polyether resin, a polyester resin, astyrene-butadiene block copolymer, a petroleum resin, a xylene resin, aketone resin, a cellulose resin, a fluoropolymer or a silicone polymer,to the positive-tone radiation-sensitive composition of the presentinvention, provided the objects and effects of the present invention arenot impaired.

[0180] Moreover, other additives that can be favorably added includepolymerization inhibitors, polymerization initiation auxiliaries,leveling agents, wettability improvers, surfactants, plasticizers,ultraviolet absorbers, antioxidants, antistatic agents, and silanecoupling agents.

[0181] [Pattern Formation Method]

[0182] A method of forming a pattern using the positive-toneradiation-sensitive composition of the present invention is to firstapply the positive-tone radiation-sensitive composition of the presentinvention onto a substrate, then semi-cure by heating, then expose withradiation in a pattern, then carry out post-exposure baking to promote aneutralization reaction, and then remove the exposed parts using adeveloping solution.

[0183] A description will now be given citing specific examples.

[0184] [1] Preparation of Substrate

[0185] First, a substrate having a flat surface is prepared. There areno particular limitations on the type of the substrate, but for examplea silicon substrate, a glass substrate or the like can be used.

[0186] [2] Formation of Coating Film

[0187] The positive-tone radiation-sensitive composition is applied ontothe substrate, and dried or heated to form a coating film.

[0188] Here, as the method of applying the positive-toneradiation-sensitive composition, a method such as a spin coating method,a dipping method, a spraying method, a bar coating method, a rollcoating method, a curtain coating method, a gravure printing method, asilk screen method, or an ink jet method can be used. Out of these, itis particularly preferable to use the spin coating method, since acoating film having a particularly uniform thickness can be obtained.

[0189] Moreover, to make the rheological properties of the positive-toneradiation-sensitive composition suitably match the application method,it is preferable to blend in any of various leveling agents,thixotropy-bestowing agents, fillers, organic solvents, surfactants andso on as required.

[0190] Moreover, it is preferable to prebake the coating film made fromthe positive-tone radiation-sensitive composition at a temperature inthe range of 50 to 200° C. after the application. Here, a semi-curedstate, in which the coating film will dissolve in the developingsolution but there is no tackiness, is preferable, and hence thetemperature range of 50 to 150° C. is more preferable.

[0191] [3] Irradiation

[0192] The upper surface of the coating film is irradiated withradiation in a prescribed pattern, for example via a photomask having aline pattern.

[0193] The method of irradiating in the prescribed pattern is notlimited to a method using a photomask comprising parts through which theradiation can pass and parts through which the radiation cannot pass.Examples of other methods are the following methods a to c.

[0194] a. A method using means for electrooptically forming a mask imagecomprising regions through which the radiation can pass and regionsthrough which the radiation cannot pass in the prescribed pattern, usinga similar principle to a liquid crystal display apparatus.

[0195] b. A method in which a light-guiding member comprising a bundleof many optical fibers is used, and irradiation is carried out via theoptical fibers in the prescribed pattern of the light-guiding member.

[0196] c. A method in which laser light, or convergent radiationobtained using a converging optical system such as a lens or a mirror,is irradiated onto the radiation-curable composition while beingscanned.

[0197] Moreover, there are no particular limitations on the radiationdose, but it is preferable to carry out the exposure by irradiating withradiation of wavelength of 200 to 390 nm and intensity of 1 to 500mW/cm² such that the radiation dose is 10 to 5,000 mJ/cm².

[0198] Here, regarding the type of the irradiated radiation, visiblelight, ultraviolet radiation, infrared radiation, X-rays and so on canbe used, but ultraviolet radiation is particularly preferable. Moreover,as the radiation (e.g. ultraviolet radiation) irradiating apparatus, itis preferable to use, for example, a high-pressure mercury lamp, alow-pressure mercury lamp, a metal halide lamp, or an excimer lamp.

[0199] Through the irradiation, acid is generated from component (B),and a neutralization reaction with component (C) in the coating filmtakes place only at the places where the positive-toneradiation-sensitive composition is irradiated.

[0200] [4] Heating Treatment

[0201] Next, after the exposure, to promote the neutralization reactionat the exposed parts, it is preferable to carry out heating treatment.The heating conditions will vary according to the components'composition of the positive-tone radiation-sensitive composition, thetypes of additives, and so on, but the temperature is generally in therange of 30 to 200° C., preferably 50 to 150° C.

[0202] [5] Developing

[0203] The coating film that has been selectively cured by exposing withradiation in a prescribed pattern as described above can be developedutilizing the difference in solubility between the cured parts and theuncured parts. After the patterned exposure, it is thus possible toremove the uncured parts while leaving behind the cured parts, resultingin formation of a positive-tone pattern.

[0204] Here, as the developing solution, it is possible to use, forexample, an organic solvent, or an alkaline aqueous solution containingan alkali such as sodium hydroxide, potassium hydroxide, sodiumcarbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine,n-propylamine, diethylamine, di-n-propylamine, triethylamine,methyldiethylamine, N-methylpyrrolidone, dimethylethanolamine,triethanolamine, tetramethylammonium hydroxide, tetraethylammoniumhydroxide, choline, pyrrole, piperidine,1,8-diazabicyclo[5.4.0]-7-undecene, or 1,5-diazabicyclo[4.3.0]-5-nonane.

[0205] Moreover, in the case of using an alkaline aqueous solution, itis preferable that the concentration thereof is generally in the rangeof 0.05 to 25 wt %, preferably in the range of 0.1 to 3.0 wt %.

[0206] Furthermore, it is also favorable to add a suitable amount of awater-soluble organic solvent such as methanol or ethanol, a surfactantor the like to such an alkaline aqueous solution, and use the mixtureobtained as the developing solution.

[0207] Moreover, the developing time is generally 30 to 600 seconds, andas the developing method, a publicly known method such as a liquidmounting method, a dipping method, or a showering developing method canbe used.

[0208] In the case of using an organic solvent as the developingsolution, a patterned coating film can be formed by air drying, wherebymoisture is removed from the surface. In the case of using an alkalineaqueous solution, a patterned coating film can be formed by washing inrunning water, for example 30 to 90 seconds, and subsequent air dryingusing compressed air, compressed nitrogen or the like, whereby moistureis removed from the surface.

[0209] [6] Heating Treatment after Developing

[0210] Next, to further cure the patterned parts, heating treatment iscarried out, for example, at a temperature of 30 to 400° C. for 5 to 60minutes using a heating apparatus such as a hotplate or an oven, wherebya cured coating film is formed.

[0211] In this way, varnish that constitutes the positive-toneradiation-sensitive composition is condensed in a promoted way by thebasic compound, and through the acid generated through the patternedexposure by irradiation, neutralization occurs only at the irradiatedparts, whereby a positive-tone cured product having excellent patternprecision can be obtained.

[0212] The positive-tone radiation-sensitive composition of the presentinvention can be effectively used for optical waveguides, insulatingfilms, protective films, and so on.

[0213] [Optical Waveguide Formation Method]

[0214] A method of forming an optical waveguide using the positive-toneradiation-sensitive composition (i.e. composition for optical waveguideformation) of the present invention is constituted primarily from alower clad layer formation step, a core portion formation step, and anupper clad layer formation step.

[0215] Note that in the following description, the composition foroptical waveguide formation is used for each of the lower clad layer,the core portion and the upper clad layer, but it is also possible, forexample, to use the composition for optical waveguide formation only forthe core portion. In this case, it is preferable to use a publicly knownoptical waveguide material such as quartz glass for the lower clad layerand the upper clad layer.

[0216] Moreover, to make the rheological properties of the compositionfor optical waveguide formation suitable for the actual applicationmeans, it is preferable to blend in any of various leveling agents,thixotropy-bestowing agents, fillers, organic solvents, surfactants andso on as required.

[0217] The core portion, the lower clad layer and the upper clad layercan be formed through a similar procedure to the pattern formationmethod described above.

[0218] [Structure of Optical Waveguide]

[0219] An example of the constitution of an optical waveguide of thepresent invention will now be described with reference to the drawings.FIG. 1 is a sectional view of an example of the optical waveguide of thepresent invention, and FIG. 2 is a perspective view of another exampleof the optical waveguide of the present invention.

[0220] First, the optical waveguide 10 shown in FIG. 1 is formed from asubstrate 12 that extends in a direction perpendicular to the plane ofthe paper (i.e. the light waveguiding direction), and a lower clad layer13, a core portion 15 and an upper clad layer 17, which are formed inthis order on the substrate 12.

[0221] Regarding the core portion 15, for the purpose of not leaking outthe waveguided light from the sides, a constitution is adopted in whichthe width of the core portion 15 in the transverse sectional directionrelative to the light waveguiding direction is made to be narrower thanthe corresponding width of the upper clad layer 17 and the lower cladlayer 13, and the upper clad layer 17 goes around the sides of the coreportion 15. That is, the constitution is such that the whole of the coreportion 15 is embedded in the body comprising the lower clad layer 13and the upper clad layer 17 stacked up on one another.

[0222] Note that in the example shown in FIG. 1, only one core portion15 is provided, but a plurality of core portion 15 may be providedparallel to one another.

[0223] Moreover, in the example of the optical waveguide shown in FIG.1, the constitution is such that the upper clad layer 17 goes around thesides of the core portion 15, but as shown in FIG. 2, a constitution maybe adopted in which the core portion 15 has a semicircular cylindershape, and the lower clad layer 13 goes around the periphery of the coreportion 15. Furthermore, although not shown in the drawings, an opticalwaveguide constitution, in which the upper clad layer is made to goaround only one side of the core portion, and the lower clad layer ismade to go around the other side of the core portion, may be adopted.

[0224] Moreover, to carry out light waveguiding more efficiently, asshown in FIG. 2, it is also favorable to integrally provide a ridge part18 above the core portion 15. There are no particular limitations on theform of the ridge part 18, but for example it is favorable to make thecross-sectional shape be a trapezoid.

[0225] In the optical waveguide 10 having a constitution as describedabove, there are no particular limitations on the thicknesses of thelower clad layer 13, the upper clad layer 17 and the core portion 15,but for example it is preferable to make the thickness of the lower cladlayer 13 be in the range of 3 to 50 μm, the thickness of the coreportion 15 be in the range of 3 to 20 μm, and the thickness of the upperclad layer 17 be in the range up to 50 μm.

[0226] Moreover, there are no particular limitations on the width of thecore portion 15 in the transverse sectional direction relative to thelight waveguiding direction, but it is preferable to make this width,for example, be in the range of 1 to 50 μm.

[0227] Moreover, with the optical waveguide 10, it is necessary to makethe refractive index of the core portion 15 be greater than therefractive indexes of the lower clad layer 13 and the upper clad layer17. To obtain excellent waveguiding properties, it is preferable to makethe refractive index of the core portion 15 be in the range of 1.450 to1.650, and the refractive index of the lower clad layer 13 and the upperclad layer 17 be in the range of 1.400 to 1.648, for light of wavelengthof 1300 to 1600 nm.

[0228] Moreover, it is preferable to set the refractive index of thecore portion 15 considering the values of the refractive index of thelower clad layer 13 and the upper clad layer 17. It is particularlypreferable to make the refractive index of the core portion 15 be avalue greater than the value of the refractive index of the lower cladlayer 13 and the upper clad layer 17 by 0.002 to 0.5.

[0229] Note that the waveguide of the present invention has thedistinctive feature that the refractive index value can easily bechanged by suitably changing the type of the hydrolyzable silanecompounds in the composition for optical waveguide formation, or byadding a hydrolyzable titanium compound, or doping with a rare earthelement.

EXAMPLES

[0230] Following is a description of Examples of the present invention.The present invention is not limited to these Examples. Moreover, in theExamples, the contents of the various components are expressed as partsby weight unless otherwise stated.

[0231] [Preparation of Radiation-Sensitive Compositions]

[0232] (1) Polysiloxane Solution 1

[0233] Methyltrimethoxysilane (304.42 g, 2.23 mol) andphenyltrimethoxysilane (230.33 g, 1.16 mol), propylene glycol monomethylether (150 g), and an Al catalyst (0.2 g, 0.005 wt %) were put into avessel equipped with a stirrer, and the vessel was immersed in an oilbath at 60° C., and stirring was carried out for 15 minutes. Once thetemperature inside the vessel had reached 60° C., a prescribed amount ofion exchange water having an electrical conductivity of 8×10⁻⁵ S·cm⁻¹(244.15 g, 13.56 mol) was added. Stirring was then carried out for 5hours, thus hydrolyzing the methyltrimethoxysilane and thephenyltrimethoxysilane. Next, acetylacetone (30 g, 0.30 mol) was added,and then the methanol produced through the hydrolysis was removed usingan evaporator. Ultimately, a propylene glycol monomethyl ether solutioncontaining a polysiloxane with the solid content made to be 65 wt % wasobtained. This shall be referred to as ‘polysiloxane solution 1’.

[0234] (2) Polysiloxane Solution 2

[0235] Methyl methacrylate (375 g, 3.74 mol), 2-hydroxypropyl acrylate(75 g, 0.64 mol), methacryloxypropyltrimethoxysilane (50 g, 0.20 mol)propylene glycol monomethyl ether (1250 g), and2,2′-azobis-(2,4-dimethylvaleronitrile) (35 g, 0.14 mol) were put into avessel equipped with a stirrer, and the system was purged with nitrogen.The temperature inside the reaction vessel was then set at 70° C., andstirring was carried out for 6 hours. Ultimately, a propylene glycolmonomethyl ether solution containing an acrylic polymer with the solidcontent made to be 28 wt % was obtained. This shall be referred to as‘acrylic polymer solution 1’.

[0236] Acrylic polymer solution 1 (133.93 g), methyltrimethoxysilane(85.62 g, 0.62 mol), dimethyldimethoxysilane (45.60 g, 0.38 mol),phenyltrimethoxysilane (64.78 g, 0.33 mol), propylene glycol monomethylether (11.27 g), and an Al catalyst (0.1 g, 0.005 wt %) were put into avessel equipped with a stirrer, and the vessel was immersed in an oilbath at 60° C., and stirring was carried out for 15 minutes. Once thetemperature inside the vessel had reached 60° C., a prescribed amount ofion exchange water having an electrical conductivity of 8×10⁻⁵ S·cm⁻¹(81.67 g, 4.52 mol) was added. Stirring was then carried out for 5hours, thus hydrolyzing the methyltrimethoxysilane and thephenyltrimethoxysilane. Next, acetylacetone (15 g, 0.15 mol) was added,and then the methanol produced through the hydrolysis was removed usingan evaporator. Ultimately, a propylene glycol monomethyl ether solutioncontaining a polysiloxane with the solid content made to be 65 wt % wasobtained. This shall be referred to as ‘polysiloxane solution 2’.

[0237] (3) Polysiloxane Solution 3

[0238] Phenyltrimethoxysilane (414.59 g, 2.09 mol) and tetraethoxysilane(103.99 g, 0.50 mol), propylene glycol monomethyl ether (225 g), and anAl catalyst (0.2 g, 0.005 wt %) were put into a vessel equipped with astirrer, and the vessel was immersed in an oil bath at 60° C., andstirring was carried out for 15 minutes. Once the temperature inside thevessel had reached 60° C., a prescribed amount of ion exchange waterhaving an electrical conductivity of 8×10⁻⁵ S·cm⁻¹ (186.36 g, 10.36 mol)was added. Stirring was then carried out for 5 hours, thus hydrolyzingthe methyltrimethoxysilane and the phenyltrimethoxysilane. Next,acetylacetone (30 g, 0.30 mol) was added, and then the methanol producedthrough the hydrolysis was removed using an evaporator. Ultimately, apropylene glycol monomethyl ether solution containing a polysiloxanewith the solid content made to be 65 wt % was obtained. This shall bereferred to as ‘polysiloxane solution 3’.

[0239] (4) Polysiloxane Solution 4

[0240] Styrene monomer (525 g, 5.04 mol), 2-hydroxyethyl acrylate (150g, 1.30 mol), methacryloxypropyltrimethoxysilane (75 g, 0.30 mol),propylene glycol monomethyl ether (750 g), and2,2′-azobis-(2-methylpropionitrile) (22.5 g, 0.13 mol) were put into avessel equipped with a stirrer, and the system was purged with nitrogen.The temperature inside the reaction vessel was then set at 80° C., andstirring was carried out for 6 hours. Ultimately, a propylene glycolmonomethyl ether solution containing an acrylic polymer with the solidcontent made to be 48 wt % was obtained. This shall be referred to as‘acrylic polymer solution 2’.

[0241] Acrylic polymer solution 2 (375 g), methyltrimethoxysilane (80.98g, 0.59 mol), phenyltrimethoxysilane (123.00 g, 0.62 mol), propyleneglycol monomethyl ether (105.00 g), and an Al catalyst (0.07 g, 0.005 wt%) were put into a vessel equipped with a stirrer, and the vessel wasimmersed in an oil bath at 60° C., and stirring was carried out for 15minutes. Once the temperature inside the vessel had reached 60° C., aprescribed amount of ion exchange water having an electricalconductivity of 8×10⁻⁵ S·cm⁻¹ (81.67 g, 4.52 mol) was added. Stirringwas then carried out for 5 hours, thus hydrolyzing themethyltrimethoxysilane and the phenyltrimethoxysilane. Next,acetylacetone (15 g, 0.15 mol) was added, and then the methanol producedthrough the hydrolysis was removed using an evaporator. Ultimately, apropylene glycol monomethyl ether solution containing a polysiloxanewith the solid content made to be 65 wt % was obtained. This shall bereferred to as ‘polysiloxane solution 4’.

[0242] [Preparation of Compositions for Optical Waveguide Formation]

[0243] (1) Preparation of Positive-Tone Radiation-Sensitive CompositionA (used as Core Material) for Optical Waveguide Formation

[0244] 0.1 parts by weight of a photoacid generator((4,7-dibutoxy-1-naphthylene)dimethylsulfone trifluoromethanesulfonate),0.025 parts by weight of a basic compound (i.e. a compound made fromtetramethylammonium hydroxide and acetic acid), and 0.05 parts by weightof SH28PA (made by Dow Corning Toray Silicone Co., Ltd.) as a siliconesurfactant were added to 100 parts by weight (in terms of solid content)of polysiloxane solution 1, and mixing to homogeneity was carried out,thus obtaining a positive-tone radiation-sensitive composition A.

[0245] (2) Preparation of Positive-Tone Radiation-Sensitive CompositionB (used as Clad Material) for Optical Waveguide Formation

[0246] 0.1 parts by weight of a photoacid generator((4,7-dibutoxy-1-naphthylene)dimethylsulfone trifluoromethanesulfonate),0.025 parts by weight of a basic compound (i.e. a compound made fromtetramethylammonium hydroxide and acetic acid), and 0.05 parts by weightof SH28PA (made by Dow Corning Toray Silicone Co., Ltd.) as a siliconesurfactant were added to 100 parts by weight (in terms of solid content)of polysiloxane solution 2, and mixing to homogeneity was carried out,thus obtaining a positive-tone radiation-sensitive composition B.

[0247] (3) Preparation of Positive-Tone Radiation-Sensitive CompositionC (used as Core Material) for Optical Waveguide Formation

[0248] 0.1 parts by weight of a photoacid generator((4,7-dibutoxy-1-naphthylene)dimethylsulfone trifluoromethanesulfonate),0.025 parts by weight of a basic compound (i.e. a compound made fromtetramethylammonium hydroxide and acetic acid), and 0.05 parts by weightof SH28PA (made by Dow Corning Toray Silicone Co., Ltd.) as a siliconesurfactant were added to 100 parts by weight (in terms of solid content)of polysiloxane solution 3, and mixing to homogeneity was carried out,thus obtaining a positive-tone radiation-sensitive composition C.

[0249] (4) Preparation of Positive-Tone Radiation-Sensitive CompositionD (Used as Clad Material) for Optical Waveguide Formation

[0250] 0.1 parts by weight of a photoacid generator((4,7-dibutoxy-1-naphthylene)dimethylsulfone trifluoromethanesulfonate),0.025 parts by weight of a basic compound (i.e. a compound made fromtetramethylammonium hydroxide and acetic acid), and 0.05 parts by weightof SH28PA (made by Dow Corning Toray Silicone Co., Ltd.) as a siliconesurfactant were added to 100 parts by weight (in terms of solid content)of polysiloxane solution 4, and mixing to homogeneity was carried out,thus obtaining a positive-tone radiation-sensitive composition D.

Example 1

[0251] Composition B for optical waveguide formation was applied ontothe surface of a silicon substrate using a spin coater, drying wascarried out for 10 minutes at 80° C., and then heating was carried outfor 1 hour at 200° C., thus forming a lower clad layer having athickness of 10 μm. The refractive index of this lower clad layer tolight of wavelength 1550 nm was 1.4628.

[0252] Next, composition A for optical waveguide formation was appliedonto the lower clad layer using a spin coater, drying was carried outfor 3 minutes at 80° C., and then using a photomask having an opticalwaveguide pattern of width of 4 to 20 μm, exposure was carried out byirradiating with ultraviolet radiation of wavelength of 365 nm andintensity of 200 mW/cm² for 5 seconds. Next, the irradiated coating filmwas heated for 2 minutes at 100° C. After that, the substrate wasimmersed in a developing solution comprising a 1.8 wt %tetramethylammonium hydroxide (TMAH) aqueous solution, thus dissolvingthe exposed parts. After that, heating was carried out for 1 hour at200°C., thus forming a core portion having a thickness of 7 μm. Therefractive index of the obtained core portion to light of wavelength1550 nm was 1.4685.

[0253] Composition B for optical waveguide formation was further appliedonto the upper surface of the lower clad layer having the core portionthereon using a spin coater, drying was carried out for 10 minutes at80° C., and then heating was carried out for 1 hour at 200° C., thusforming an upper clad layer having a thickness of 15 μm, whereby anoptical waveguide was formed. The refractive index of the formed upperclad layer to light of wavelength 1550 nm was 1.4628.

[0254] For the optical waveguide obtained in this way, light ofwavelength 1300 nm and 1550 nm was inputted into one end of thewaveguide, and the quantity of light emerging from the other end wasmeasured using a power meter. The result was that the waveguide loss forthe optical waveguide was less than 0.3 and 0.7 dB/cm respectively forthe two cases.

Example 2

[0255] Composition D for optical waveguide formation was applied ontothe surface of a silicon substrate using a spin coater, drying wascarried out for 10 minutes at 80° C., and then heating was carried outfor 1 hour at 200° C., thus forming a lower clad layer having athickness of 10 μm. The refractive index of this lower clad layer tolight of wavelength 1550 nm was 1.5236.

[0256] Next, composition C for optical waveguide formation was appliedonto the lower clad layer using a spin coater, drying was carried outfor 1 minute at 80° C., and then using a photomask having an opticalwaveguide pattern of width of 4 to 20 μm, exposure was carried out byirradiating with ultraviolet radiation of wavelength of 365 nm andintensity of 200 mW/cm² for 5 seconds. Next, the irradiated coating filmwas heated for 2 minutes at 100° C. After that, the substrate wasimmersed in a developing solution comprising a 1.8 wt %tetramethylammonium hydroxide (TMAH) aqueous solution, thus dissolvingthe exposed parts. After that, heating was carried out for 1 hour at200° C., thus forming a core portion having a thickness of 7 μm. Therefractive index of the obtained core portion to light of wavelength1550 nm was 1.5285.

[0257] Composition D for optical waveguide formation was further appliedonto the upper surface of the lower clad layer having the core portionthereon using a spin coater, drying was carried out for 10 minutes at80° C., and then heating was carried out for 1 hour at 200° C., thusforming an upper clad layer having a thickness of 15 μm, whereby anoptical waveguide was formed. The refractive index of the formed upperclad layer to light of wavelength 1550 nm was 1.5236.

[0258] For the optical waveguide obtained in this way, light ofwavelength 1300 nm and 1550 nm was inputted into one end of thewaveguide, and the quantity of light emerging from the other end wasmeasured using a power meter. The result was that the waveguide loss forthe optical waveguide was less than 0.3 and 0.4 dB/cm respectively forthe two cases.

1. A positive-tone radiation-sensitive composition, comprising: (A) atleast one compound selected from the group consisting of a hydrolyzablesilane compound represented by general formula (1), hydrolyzates thereofand condensates thereof (R¹)_(p)Si(X)_(4-p)   (1) (wherein R¹ is anon-hydrolyzable organic group having 1 to 12 carbon atoms, X is ahydrolyzable group, and p is an integer from 0 to 3); (B) a photoacidgenerator; and (C) a basic compound.
 2. The positive-toneradiation-sensitive composition according to claim 1, further comprisingan acrylic polymer as a component (D).
 3. The positive-toneradiation-sensitive composition according to claim 1, further comprisingan organic solvent.
 4. The positive-tone radiation-sensitive compositionaccording to claim 1, wherein said basic compound is a compound capableof reacting with said photoacid generator.
 5. A positive-toneradiation-sensitive composition for optical waveguides, comprising: (A)at least one compound selected from the group consisting of ahydrolyzable silane compound represented by general formula (1),hydrolyzates thereof and condensates thereof (R¹)_(p)Si(X)_(4-p)   (1)(wherein R¹ is a non-hydrolyzable organic group having 1 to 12 carbonatoms, X is a hydrolyzable group, and p is an integer from 0 to 3); (B)a photoacid generator; and (C) a basic compound.
 6. The positive-toneradiation-sensitive composition for optical waveguides according toclaim 5, further comprising an acrylic polymer as a component (D). 7.The positive-tone radiation-sensitive composition for optical waveguidesaccording to claim 5, further comprising an organic solvent.
 8. Thepositive-tone radiation-sensitive composition for optical waveguidesaccording to claim 5, wherein said basic compound is a compound capableof reacting with said photoacid generator.
 9. A pattern formation methodcomprising: a step of applying a positive-tone radiation-sensitivecomposition, which comprises (A) at least one compound selected from thegroup consisting of a hydrolyzable silane compound represented bygeneral formula (1), hydrolyzates thereof and condensates thereof(R¹)_(p)Si(X)_(4-p)   (1) (wherein R¹ is a non-hydrolyzable organicgroup having 1 to 12 carbon atoms, X is a hydrolyzable group, and p isan integer from 0 to 3), (B) a photo acid generator, (C) a basiccompound, onto a substrate to form a coating film; a step of irradiatingdesired places of the coating film with radiation; and a step ofremoving the irradiated parts of the coating film.
 10. The patternformation method according to claim 9, further comprising a step ofheating the coating film before the irradiation, and a step of heatingthe coating film after the irradiation.
 11. The pattern formation methodaccording to claim 9, further comprising a step of developing with adeveloping solution after carrying out the heating after theirradiation.
 12. A method of forming an optical waveguide, comprising: astep of applying a positive-tone radiation-sensitive composition foroptical waveguides, which comprises (A) at least one compound selectedfrom the group consisting of a hydrolyzable silane compound representedby general formula (1), hydrolyzates thereof and condensates thereof(R¹)_(p)Si(X)_(4-p)   (1) (wherein R¹ is anon-hydrolyzable organic grouphaving 1 to 12 carbon atoms, X is a hydrolyzable group, and p is aninteger from 0 to 3), (B) a photoacid generator, and (C) a basiccompound, onto a substrate to form a coating film; a step of irradiatingdesired places of the coating film with radiation; and a step ofremoving the irradiated parts of the coating film.
 13. An opticalwaveguide which has been formed using the method according to claim 12.